Wireless doorbell systems have become an increasingly popular option for persons wishing either to replace their current doorbell or to add additional doorbell buttons at their place of residence. A general wireless doorbell system comprises at least one battery-operated, radio-frequency transmitter and a radio-frequency receiver. In response to the depression of a button on the transmitter, a radio-frequency signal is transmitted for reception by the receiver. The receiver alerts the user that the doorbell button has been depressed by producing an audible signal, such as a tone or a melody, upon detecting the transmitted radio-frequency signal.
The installation of a battery-powered wireless doorbell system is performed by simply inserting batteries into the transmitter and receiver, and mounting them at their desired locations. Because no wiring is required between the transmitter and the receiver, the resulting installation of a wireless doorbell system is a relatively easy task. This ease in installation partially accounts for the popularity of wireless doorbell systems.
One drawback of using a battery-operated wireless doorbell system is that the batteries in the transmitter and receiver must be replaced when they are insufficiently powered. In practice, the transmitter batteries need not be replaced as often as the receiver batteries. This is due to the fact that the receiver consumes battery power continually in determining whether or not a radio-frequency signal was transmitted, whereas the transmitter consumes battery power only when its button has been depressed. Typically, the batteries in the receiver need to be replaced after a number of months of operation.
Another drawback of previous wireless doorbell systems is their sensitivity to both noise and interference from other Part 15 transmitters.